The present invention generally relates to a method and an apparatus for determining the operational energy cost of a hybrid vehicle and more particularly, to a method and an apparatus for determining the amount of energy expended by a hybrid vehicle, effective to evaluate various vehicle designs and operational strategies and to allow relatively accurate operational simulation studies to be conducted.
A hybrid vehicle includes at least two sources of torque type energy which are alternatively used to power or operate the vehicle (i.e. the respectively generated torque energy is communicated to the wheels of the vehicle, effective to allow the hybrid vehicle to be selectively operated). Typically, a first source of energy comprises an internal combustion engine which utilizes hydrocarbon type fuel to provide the desired power. A second source of energy usually comprises an electric battery in combination with a motor. The battery is selectively and periodically xe2x80x9crechargedxe2x80x9d by the operating internal combustion engine in order to ensure the continued availability of the second energy source. The electric battery therefore desirably allows the use of the hydrocarbon fuel to be reduced and allows for a desired reduction in the various undesirable by-products produced by the use of such fuel.
It is relatively difficult to determine the cost or the amount of energy utilized by such a hybrid vehicle due to the use of multiple energy sources and due to the use of at least one of the energy sources to provide power or electrical energy to the other, thereby preventing or substantially hindering the creation of a relatively accurate energy consumption or energy cost model, preventing or substantially hindering the creation of a relatively accurate operational simulation of such a hybrid vehicle, and preventing or substantially hindering the ability to accurately assess various design configurations and operational strategies. While some techniques do attempt to determine such energy cost or consumption, they are not accurate and do not reliably estimate or determine such costs.
There is therefore a need for a method and an apparatus for determining the operational energy cost for a hybrid vehicle in a manner which overcomes at least some of the previously delineated drawbacks of prior techniques.
It is a first object of the present invention to provide a method and an apparatus for determining the operational energy cost of a hybrid vehicle in a manner which overcomes at least some of the previously delineated drawbacks.
It is a second object of the present invention to provide a method and an apparatus for determining the operational energy cost of a hybrid vehicle in a manner which overcomes at least some of the previously delineated drawbacks and which utilizes the state of charge or an initial charge placed within the battery.
According to a first aspect of the present invention an apparatus for determining the operational energy cost for a hybrid vehicle is provided. The apparatus comprises a controller which dynamically computes an equivalent battery energy cost and which uses the dynamically computed cost to determine the operational energy cost for a hybrid vehicle.
According to a second aspect of the present invention, a method is provided for determining the operational cost of a hybrid vehicle. The method includes the steps of computing a discharge efficiency; computing a recharge efficiency; computing an amount of energy supplied from regenerative braking, and using said computed charge efficiency, recharge efficiency, and said amount of energy to determine the operational cost of said vehicle.
These and other features, aspects, and advantages of the present invention will become apparent from a reading of the following detailed description of the preferred embodiment of the invention and by reference to the following drawings.